NAJAF, Iraq — It had been quite the morning for Jamli Umm Saif, a mother of four. After morning prayers Saturday, she sent off her husband and eldest son to join a military parade by the Mahdi Army, a Shiite militia run by the populist cleric Muqtada al-Sadr.

Then she rang up her girlfriends, and told them to come watch the parade wearing white shrouds draped over their black chadors, as a sign that they too, the women of the Mahdi Army, were ready for martyrdom.

“Yes, we are women,” said Umm Saif, a nickname meaning “mother of Saif,” giggling from behind her black face cover. “But don’t be mistaken. We can fight too. We will all fight.”

Here in the Shiite heartland of Iraq, volunteers have revived battalions of the Mahdi Army, one of the dominant groups preparing for battle following the call for a “defensive jihad” June 13 by Grand Ayatollah Ali al-Husseini al-Sistani, one of the highest authorities in the Shiite faith.

From the sidelines of the parade on a main street in Najaf, Umm Saif, 47, and her friends waved green flags, one of the colors of Shiite Islam, as their men marched by the thousands, singing in support of al-Sadr.

The cleric himself, who only recently returned from Iran, where he is studying theology, was not present, but his “army,” which he had disbanded in 2008, seemed to be back in full strength.

The Mahdi Army march was the largest of several taking place Saturday in Najaf, the oldest center of Shiite learning and home to several key clerics influential with the faithful.

All factions in the city have started mobilizing, preparing, as they call it, “for war.” But, almost everybody here says, the war is against the “terrorists” — the jihadists of the Islamic State of Iraq and the Levant who have seized broad stretches of northern territory — and not against Sunnis.

This reluctance to lump together the Sunnis of the Islamic State of Iraq and the Levant with the Sunnis of Iraq suggests that some Shiites, the majority sect in the country, are heeding the call of al-Sistani and other clerics to embrace a national identity instead of a religious one, despite months of fierce sectarian battles across Iraq that preceded the Islamic State of Iraq and the Levant invasion two weeks ago. Several ayatollahs have issued fatwas against anyone feeding the fire of sectarianism.

On Friday, a spokesman for al-Sistani warned that if the Islamic State of Iraq and the Levant was not “fought and expelled from Iraq, everyone will regret it tomorrow, when regret has no meaning.”

That day, as the sun was setting, Najaf and the adjacent city of Kufa were bustling with activity to heed that call. In neighborhoods, on soccer pitches and in parades on the main highway that splits the city in half, cheerful Iraqis brandished machine guns, denouncing the “terrorists.”

Sheikh Foad al-Torfa, a round-bellied man of God, trained on a dusty field in Kufa in military fatigues, a white turban the only reminder of his life as a Shiite Muslim cleric.

All around him groups of black-clad men marched in formation. “Who are you fighting for?” a self-appointed drill sergeant shouted. “For Iraq, for Iraq,” the men thundered in reply.

“When I looked at myself in the mirror, I felt proud, and powerful,” said al-Torfa, wiping sweat from his forehead. An Iraqi army belt was strapped around his waist, and every now and then he touched the pistol hanging from it.

Among the long procession of war-hungry men seemingly present everywhere in Najaf on Friday were members of the Shebil tribe, who gathered after lunch on an empty parking lot. Members of the tribe popped up around the corner, dancing and singing with weapons in their hands, joining an ever-growing forest of gun barrels pointing in the air.

“Daesh, where are you? The real men are entering the battlefield,” they sang, using the Arabic name for the Islamic State of Iraq and the Levant. A 10-year-old boy nearly tripped over the Kalashnikov machine gun he was struggling to carry. “Tell them you will fight the terrorists,” his father said.

The Shebil, whose name translates as “lion cubs,” have already gathered 2,000 volunteers, said their leader, Sheikh Riyad al-Shaban. He and other tribal elders sat on a row of plastic chairs overlooking the gathering.

“This is not about Sunnis or Shia,” al-Shaban said. But when the dust settles, those who cooperated with the Islamic State of Iraq and the Levant must face justice, he said. “The Iraqi people will never forget what those traitors have done.”

As his men set out on a procession through town, waving red Shiite flags and escorted by the Iraqi army, al-Shaban said he expected the United States to honor the security agreement it reached with Prime Minister Nouri al-Maliki.

“Obama has signed it, al-Maliki has signed it, where are the Americans to help us?” he asked.

Around the shrine of the Imam Ali Mosque in Najaf, the tomb of one the most revered saints in Shiism, pilgrims with ice cream cones pushed baby strollers.

But in the offices in the back alleys around the shrine, clerics were receiving frantic phone calls from across the country.

“A new attack on the Baiji oil terminal,” said Ali al-Najafi, son of Grand Ayatollah Hossein Bashir al-Najafi.

He was working three phones at the same time and his aides kept slipping him notes with more news. “Welcome to the battlefield,” he said, sighing.

Al-Najafi stressed that al-Sistani’s call for jihad must not be interpreted as sectarian, and explained that despite the fact that Shiites are the majority, all Iraqi groups must have their share of power.

“Many of us here in Najaf have long been criticizing Mr. al-Maliki,” he said. “He made many, many mistakes, but now we must first focus on removing the terrorists from Iraq.”

At the main entrance to the shrine, fresh victims arrived from the escalating war up north. Just after noon prayers Saturday, dozens of armed men of the Shiite Asaib Ahl al-Haq militia pulled up at the front entrance, unloaded a coffin and marched toward the mausoleum of Imam Ali.

In the courtyard, a cleric spoke in honor of Asad al-Saeedi, 38, who was killed after entering a booby-trapped room near Fallujah, an Islamic State of Iraq and the Levant-controlled area.

“Our enemies are sneaky and unfair,” the cleric said as dozens of fighters sat at his feet. “But do not underestimate them.”

After that, a column of cars escorted the body of al-Saeedi to an immense cemetery on the outskirts of Najaf, the Wadi al-Salaam.

There, Ali Jassem, 48, a friend of al-Saeedi’s who was with him on his deadly mission, sat on one of the countless tombstones, smoking a cigarette as undertakers widened the hole dug for the fighter’s large body.

“Many more martyrs will follow,” said Jassem. “I wish I will be one of them too.”